gen.txt

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johnbowens
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49638
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gen.txt
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2011-12-29 16:33:05
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general electrical JATC
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general electrical theory
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  1. what in a set of prints contains detailed information about what size and type of materials are to be used on a job? (NC set: general)
    schedules
  2. What is a list of detailed job requirements under which all work must be performed? (NC set: general)
    specifications: usually printed on 81/2 x 11 paper and bound
  3. What is the difference between addendums, revisions, and change orders? (NC set: general)
    • An addaddendum occurs before bid (addendum is adding)
    • Revisions dated changes in prints or specs with a cloud around it
    • change orders occur after bids are opened and MUST BE SIGNED in order to ensure payment
  4. What must be done daily and eventually turned in to the contractor before payment is made? (NC set: general)
    Working drawings or as-builts
  5. All horizontal and vertical measurements begin from this point? (NC set: general)
    point of beginning: could be a stake or pin buried in the ground
  6. What schedule provides mounting and routing info for electrical devices and is used primarily on commercial or industrial prints? (NC set: general)
    room schedules
  7. What schedule lists and identifies circuit branches? (NC set: general)
    panel schedules
  8. In a residential application the lighting schedule may be replaced by a ________ ______ that the owner will use to select their lighting at a local store? (NC set: general)
    lighting allowance
  9. Floor plans usually are represented by a cutting plane at ____ feet height with objects below the line represented by a solid line and above represented by a hidden line. (NC set: general)
    5
  10. cabinets are in sizes __ inches wide and ___ increments thereafter. (NC set: general)
    9 and 3
  11. ____ plan will tell you about exterior lighting and relationships to exterior buildings. A.K.A. sight plan. It will also tell you where to locate the service. (NC set: general)
    Plot plan
  12. ___ _______ diagram shows you where panels go and how they are connected. (NC set: general)
    One line
  13. What scale is based on 1/2 inch and 1/4 inch? (NC set: general)
    Mechanical engineer’s scale
  14. If there is no information on what height to place a switch then you do what? (NC set: general)
    Use standard practice- 48 inches.
  15. Where do you find information about circuit breakers? (NC set: general)
    The panel schedule
  16. Who had the authority to make changes? (NC set: general)
    The architect
  17. What is the smallest of the standard architectural print sizes? (NC set: general)
    A
  18. The maximum irradiance at any point on the Earth is what? Measured with what? (NC set: general)
    • 1000 watts/ meter squared
    • pyrometer
  19. North azimuth for a compass is what degree? (NC set: general)
    00 or 3600
  20. 0 degrees for a solar calculation is what? (NC set: general)
    South, and working counter clockwise. East is 90, west is 270
  21. The panel is greater than 10 feet from the inverter, what must be used? (NC set: general)
    A disconnect
  22. The standard used to investigate snap switches would be? (NC set: general)
    Ul20
  23. The white book assists with NEC _______. (NC set: general)
    Enforcement
  24. Width of a working space must be _____ or the width of the panel, whichever is greater. (NC set: general)
    30 inches
  25. The door of an electrical panel has to be able to open how far? (NC set: general)
    90 degrees
  26. Headroom is what height? What is dedicated space? (NC set: general)
    6.5 feet / 6 feet above equipment
  27. The parts of a 3 way switch are? (NC set: general)
    • ______traveler
    • Shunt ___
    • ______traveler
  28. When a switch opens it is rated on its _______. (NC set: general)
    Voltage
  29. When it closes, a switch is rated for ________. (NC set: general)
    Current
  30. An illegal 3-way switch (California 3-way) controls a load by doing what? (NC set: general)
    Switching between the hot and neutral
  31. Switches in multiple always start and end with what? Meaning how many 4 ways can be used in travelers of a circuit? DC theory PP 79 (NC set: general)
    • 3-ways
    • As many 4 ways as we want
  32. The number or circuit paths we can control are called ________ and the number of positions we can close are called _________. DC theory 79 (NC set: general)
    Poles and throws.
  33. A wire .001 inches in dia. is considered ________ or _______ in diameter. (NC set: general)
    1cm or 1mil inch
  34. What is the formula for calculating cross sectional area of a conductor in cm (circular mils)? (NC set: general)
    (dia. in inches x 1000) square the result
  35. Internationally the conductor size is expressed in what? Using what formula? (NC set: general)
    Square millimeter (mm2) Using Area= p R squared (where p=3.14159 R=radius
  36. Calculating cross sectional dia. in mm squared is different from circular mils how? (NC set: general)
    Using radius in mm versus dia. in inches.
  37. I.E.C. standards for K are metric values of? (NC set: general)
    The resistance of a conductor 1m long and 1mm in diameter
  38. What is the formula for resistance in a conductor? (NC set: general)
    R=(KxL) divided by A (R-resistance, K-specific resistance, L- length, A-circular mil inch squared)
  39. To calculate CM for a rectangle use what formula? (NC set: general)
    [(LxW) x 1000] /.7854 = square mils
  40. The formula for line drop is ___________. (NC set: general)
    • VD= 2KLI/Cm
    • Mnemonic: Venereal disease = 2 Kalashnikovs divided by communists
  41. Watt loss is also known as what? What is the formula? (NC set: general)
    Line loss or heat loss. Formula is P=I^2 x R
  42. Different watt lamps have the same ________ rating. How? (NC set: general)
    Voltage. Because resistance and current are inversely proportional (change in opposite directions) while voltage will not change in the circuit.
  43. What is the formula for watts used in each component versus the entire circuit? (NC set: general)
    P= I^2xR / P=It x R1
  44. Identify the difference between a rheostat and potentiometer. (NC set: general)
    • Potentiometer- voltage three leads connected across the load
    • rheostat- current two leads, from the greek rheo meaning stream
  45. The formula for law of proportionality is what? Used in _______ for voltage and _______ for current. (NC set: general)
    • It (rt/rn) mnemonic: rt = r top
    • In parallel for current and series for voltage.
  46. Values that change in the same direction are ________ proportional and values that change in opposite directions are __________ proportional. (NC set: general)
    Directly / inversely
  47. A motor starting will draw typically ____ current as when it is running. (NC set: general)
    6 x as much
  48. A pump draws more/ less current when the inlet is plugged or closed. (NC set: general)
    Less
  49. The 0 (green) and I (red) symbol on an on/off switch is the European version of what? (NC set: general)
    Off and on. Mnemonic: off= zero current and on= 1 or some current
  50. There are 2 types of al to cu connections. What are they? (NC set: general)
    UL listed AL/ CU adapter or gutter splice
  51. There are 2 types of connectors used with aluminum conductors. (NC set: general)
    Mechanical screw type and compression type.
  52. AL AWG and CU AWG is what? (NC set: general)
    The same
  53. A solder less lug is what? (NC set: general)
    A chair lug
  54. Conductors larger than #8 AWG are what? (NC set: general)
    Stranded (test instrument pp. 24)
  55. Ampacity is based on what type of current? (NC set: general)
    Continuous
  56. More than three current carrying conductors must be ___________. (NC set: general)
    Derated
  57. A switch leg is the wire going __________ . (NC set: general)
    Directly to the device
  58. The law of magnetic poles states that ________ poles attract and ________ poles repel. (NC set: general)
    • Unlike
    • Like
  59. The formula for the resistance of a length of wire is? (NC set: general)
    • R= ?1000 feet x length x 2
    • 1000
  60. The approximation method for resistance in a length of conductor is what? (NC set: general)
    Drop the last digit from circular mils (cm) and this equals the number of feet for approximately 1 ohm resistance.
  61. The thread cap color codes for IMC are? (NC set: general)
    Orange is whole inch sizes, yellow is 1/2 inch sizes, Green is 1/4 sizes. Conduit bending PP 8 (NC set: general)
  62. The rigid Thread cap color codes are?
    Blue is whole inch size, black is 1/2 size, and Red is 1/4 sizes. Conduit bending PP 5 (NC set: general)
  63. Chapters 2, 3 & 4 in the NEC are referred to as the _____________ chapters. (NC set: general)
    Plan, build, use.
  64. The square footage of a building is measured by the ___________ of a building. When converting from feet and inches to square feet the trick is to convert to _________ form. (NC set: general)
    • Outside
    • Decimal
    • NEC 220.12
  65. When converting to yards of concrete from a dimension in feet and inches squared divide by ________. (NC set: general)
    27
  66. If a circuit is a continuous load, how much can you load the circuit? (NC set: general)
    • 80%
    • NEC
  67. Installations that comply with the NEC are considered adequate for service and future expansion. True? (NC set: general)
    • False.
    • NEC 90.1(C)
  68. What chapters of the NEC apply generally? (NC set: general)
    • 1-4
    • NEC 90.3
  69. Receptacles rated ____ amps or less and designed for the direct connection of aluminum conductors shall be marked co/alu (NC set: general)
    20 amps NEC 406.2(C)
  70. Where installed in raceways, conductors _______ awg and larger shall be stranded. (NC set: general)
    • 8 AWG and larger
    • NEC 310.3
  71. The NEC requires at least one outlet in every room be ______ for lighting. (NC set: general)
    • Switched
    • NEC
  72. The phase arrangement on 3- phase buses shall be ________ from front to back and top to bottom. The ___ phase shall be that phase having the higher voltage to ground on 3-phase, 4-wire delta-connected systems. Other bus bar arrangements shall be permitted for additions to existing installations and shall be marked. (NC set: general)
    • A,B,C,
    • B
    • NEC 408.3(E) Switchboards and panel boards
  73. For other than a totally enclosed switchboard, a space not less than _____ shall be provided between the top of the switchboard and any combustible ceiling, unless a noncombustible shield is provided between the switchboard and the ceiling. (NC set: general)
    • 3 feet
    • NEC 408.18 (a)
  74. The conduit or raceways, including their end fittings, shall not rise more than ______ above the bottom of the enclosure. (NC set: general)
    • 3 inches
    • NEC 408.5
  75. All panel boards shall have a rating not less than the _______ _______ ______required for the load calculated in accordance with parts II, III, IV, or V of article 220 as applicable. (NC set: general)
    • Minimum feeder capacity
    • NEC 408.30
  76. A cabinet can be installed up to ___ inches deep in non-combustible walls and _____ with combustible walls. (NC set: general)
    • 1/4 inches
    • flush
    • NEC 312.3
  77. Conductors ______AWG or larger shall be installed with a round insulation ring. (NC set: general)
    • 4
    • NEC 300.4(G)
  78. The NEC recommends that voltage drop on branch circuits not exceed 3% at the farthest outlet of power, heating, and lighting loads, and where the maximum total voltage drop on both feeders and branch circuits to the farthest outlet does not exceed _______. NEC 210.19 (A) 1 FPN 4 (NC set: general)
    5%
  79. If a circuit changes amplitude over time, but not polarity it is called what? (NC set: general)
    A DC circuit. (A.C. theory WB PP 14)
  80. Two sine waves of the same frequency are said to be in phase when they both cross the __________at the _________ going in _________ . A.C. theory WB PP 14 (NC set: general)
    • Reference line
    • Same time
    • Same direction
  81. A D.C. generator has _____, and an A.C. generator has______? (NC set: general)
    • commutator
    • slip-rings
  82. When ________lines of flux are cut in __________, _______ is produced. (NC set: general)
    • 1 million
    • 1 second
    • 1 volt
  83. The formula for the time required for one cycle is what? (NC set: general)
    T=1/F
  84. The ________ is the real wave form typically available at an outlet. (NC set: general)
    Peak to Peak (A.C. theory pp. 33)
  85. There are ___ measurements of voltage and current associated with a sine wave, they are: _____. Their formulas are? (NC set: general)
    • 4 measurements of voltage and current with a sine wave:
    • Peak 1.414 (RMS / EFF)
    • Effective or RMS .707 (peak)
    • Average .637 (peak)
    • Peak to Peak 2x (1.414x RMS)
  86. What value will always be larger than the RMS value? (NC set: general)
    Peak.
  87. The value not used in true AC but rather when AC is converted to DC using a full wave rectifier is? (NC set: general)
    Average (A.C. theory pp.35)
  88. The actual Average is the ________ voltages or current values across a full cycle; therefore a true A.C. sine wave has an average value of _______.
    • Instantaneous (A.C. theory pp. 35)
    • Zero
  89. RMS is also known as _____ and has the same heating effect of D.C. at that value. (NC set: general)
    Effective
  90. One important thing to remember is that in an AC circuit when a voltage value is given it is always the ________ or ________value. A.C. WB PP 40 (NC set: general)
    Effective or RMS
  91. The formula for instantaneous voltage or current values in a sine wave is? A.C. PP 32 (NC set: general)
    V instantaneous = peak (sin(theta))
  92. The theoretical purely inductive circuit consumes _______ power. Why? A.C. Theory WB PP 64 (NC set: general)
    No. Because energy is stored in the magnetic field created by the current flow through the coil
  93. Power used by the resistance of the circuit is called the _________of the circuit and is measured in watts. A.C. theory WB PP 65 (NC set: general)
    True Power
  94. When current and voltage are multiplied it is called the __________. AC theory WB PP 65 (NC set: general)
    Apparent power
  95. The Ratio of the True Power to the Apparent Power is called the _________ of the circuit. AC theory WB PP 65 (NC set: general)
    Power Factor
  96. Power Factor can range from 0 to 100 and is usually reported as a percent. The ratio is equal to the _______. A.C. theory WB PP 65 (NC set: general)
    Cosine theta
  97. A power Factor can either be _________ or ________. In which cases? A.C. theory WB PP 65 (NC set: general)
    • Leading or lagging
    • Inductive: Current lags voltage ELI Voltage leads current
    • Capacitive: Current leads voltage ICE Current leads voltage
  98. In a purely resistive A.C. circuit, current and voltage are ________. A.C. WB PP 40 (NC set: general)
    In phase with one another
  99. Inductive Reactance Xl, or CEMF (counter electromagnetic force) is 1800 out of phase with the applied voltage and causes the ________ to lag behind the applied line_____ by________. A.C. theory pp. 58 (NC set: general)
    • Current
    • Voltage
    • 900
  100. Each acute angle of a right triangle has _______ ratios associated with it. Each ratio is formed by using the lengths of _____ sides of the triangle. These six trigonometric ratios are? Math pp. 438 (NC set: general)
    • 6
    • 2
    • sine, cosine, tangent, cosecant, secant, and cotangent
  101. A physical quantity described by a single number is called a ________ quantity. math pp.472 (NC set: general)
    Scalar
  102. A physical quantity that has both a magnitude and a direction is called a _________. math pp. 472 (NC set: general)
    Vector
  103. A vector written in component form is positive and negative when? math pp. 474 (NC set: general)
    • Positive when to the right or upwards
    • Negative when left or downwards
  104. To get the component form of a vector do what? math pp. 475 (NC set: general)
    Subtract the initial point from the terminal point: Ix-Tx and Iy-Ty
  105. When a vector is in standard position, the x and y components are the coordinates of the vector's______. math pp. 475 (NC set: general)
    Terminal point
  106. If we know the component form of a vector we can find the _________ of a vector by Pythagorean Theorem, and the _________ of the vector by trigonometry. The angle theta can be found using what? math pp. 487 (NC set: general)
    • Magnitude
    • Direction
    • Tan(theta) = vy/Vx
  107. The horizontal component of a vector can be found using _________ and the vertical component can be found using _________. math PP 495 (NC set: general)
    • Cosine of theta = x
    • Sine of theta = y
  108. The equation that expresses frequency is? A.C. WB 14 (NC set: general)
    F= 1/T
  109. To calculate the times constant for a circuit have L and R values, you use the formula_______. AC WB PP 43 (NC set: general)
    T= L/R where t= one time constant
  110. One time constant is equal to _______ of maximum value. A.C. WB PP 44 (NC set: general)
    63.2%
  111. Maximum current (I max) is equal to_________. A.C. WB PP 31 (NC set: general)
    • Battery voltage rated
    • Battery internal resistance
  112. Whenever a conductor cuts through magnetic lines of flux, a(n) _________ is induced into the conductor. A.C. WB PP 41 (NC set: general)
    Voltage
  113. What is meant by the term time constant in an inductive AC circuit? AC WB PP 43 (NC set: general)
    Ratio between inductance and resistance
  114. RNC is prohibited form use where it is subjected to ambient temperatures in excess of ________ F. conduit bending PP 8 (NC set: general)

    If the length change in a run of PVC exceeds ______ due to thermal expansion, an expansion fitting must be provided. conduit bending PP 7 (NC set: general)
    122 F

    1/4" Usually in a length of approximately 100 feet of conduit in an approximate 6 degree F change. See NEC table 352.44
  115. The NEC says that there shall not be more than how many 90's (quarter bends) between pull points such as conduit bodies or boxes? conduit bending PP 4 (NC set: general)
    4

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